The same way a defective 3d printed vehicle would be returned, proof of destroying what you made for a full refund. In the case of avatar... You can't unsee the movie, maybe an equivalent dose of pain to counteract the plesure? Maybe if you can prove you only derived a few units of pleasure from it, you are compensated the delta between how much was claimed and how much was delivered.
A startup where you sell movies for prices according to how much the watcher enjoyed it might be a billion dollar idea.
A startup where you sell movies for prices according to how much the watcher enjoyed it might be a billion dollar idea.